This proposal outlines an approach for studying the regulation of enzymes which have been implicated in the development of dental caries. Dextransucrase from cariogenic streptococci will be extensively purified and characterized. Particular attention will be paid to the possible subunit structure of the enzyme and its relationship to potential allosteric regulation of the enzyme. Various potential allosteric effectors will be tested utilizing the purified enzyme in order to determine whether normal allosteric inhibitors exist for this enzyme. The regulation of dextransucrase biosynthesis will also be studied by examining the possible repressibility and inducibility of the enzyme in the presence of various potential regulators. Mutants with altered dextransucrase biosynthesis will be sought in order to examine the genetic determinants of enzyme regulation. This approach will lead to the elucidation of regulatory mechanisms operative in streptococci for controlling dextransucrase production. The identification of the natural regulators of dextransucrase activity might allow these compounds or similar analogues to be utilized in the prophylaxis of dental caries.